1. Field of the Invention
The present invention relates to an image matching method for matching images by detecting corresponding points from two images, and an image interpolation method for interpolating the image using the same.
2. Description of the Related Art
A technique of image matching to obtain association between one image and the other image is a basic technique in many technical fields such as motion detection, stereo matching, image morphing, image recognition, and video encoding.
According to Murat Tekalp, “Digital Video Processing”, Prentice Hall, 1995, a technique of image matching can be sorted to four methods. In other words, there are an optical flow method, a block data base method, a gradient method, and a Bayesian method.
The optical flow method is a method for deriving an optical flow type equation defining that “a change of luminance is constant” and obtaining a flow using the optical flow equation as condition of constraint. The block data base method is a method for obtaining a motion by block-by-block template matching. The gradient method is a method for performing matching in a direction in which luminance gradient of an image decreases. The Bayesian method is a method for obtaining plausible matching stochastically.
Japanese patent No. 2927350 discloses an image matching method using a multiple resolution filter. This method is an image matching method for generating a pyramid of a plurality of multi-resolution images by means of a plurality of multiple resolution filters, and permitting an image matching from a high speed motion to a low speed motion with a high robustness by subjecting the image pyramid to a matching process sequentially from the top thereof.
A method for obtaining a smooth mapping relation is mentioned in Japanese patent No. 2927350. However, there is a problem that constraint condition to make the mapping smooth acts on a discontinuous part of motion, resulting in that the discontinuous mapping cannot be expressed.
This is a trade off to occur always in a conventional image matching method. There is a problem that if the mapping is smoothed, it comes to be difficult to express discontinuity, and if the discontinuity is expressed, the smoothness becomes impaired.
It is an object of the present invention to provide an image matching method that even if the mapping is smoothed, discontinuity is not impaired, and even if discontinuity is expressed, smoothness is obtained, and an image interpolation method using the same.